Db4 failed to load a new module to add

A newly added.ko file insmod on db410c debian has been prompted with failure. Even if the newly generated lib/modules is replaced by the system itself, it cannot be installed with modprobe.
Here’s the log. What’s the problem? Thanks
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# insmod g_ffs.ko modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
[ 1356.723016] g_ffs: Unknown symbol usb_remove_function (err 0)
[ 1356.723170] g_ffs: Unknown symbol usb_get_function_instance (err 0)
[ 1356.728334] g_ffs: Unknown symbol usb_string_ids_tab (err 0)
[ 1356.734057] g_ffs: Unknown symbol usb_get_function (err 0)
[ 1356.739940] g_ffs: Unknown symbol ffs_single_dev (err 0)
[ 1356.745224] g_ffs: Unknown symbol usb_composite_unregister (err 0)
[ 1356.750677] g_ffs: Unknown symbol usb_put_function (err 0)
[ 1356.756658] g_ffs: Unknown symbol usb_add_function (err 0)
[ 1356.762121] g_ffs: Unknown symbol usb_composite_probe (err 0)
[ 1356.767620] g_ffs: Unknown symbol usb_composite_overwrite_options (err 0)
[ 1356.773414] g_ffs: Unknown symbol usb_otg_descriptor_alloc (err 0)
[ 1356.780184] g_ffs: Unknown symbol usb_put_function_instance (err 0)
[ 1356.786281] g_ffs: Unknown symbol usb_otg_descriptor_init (err 0)
[ 1356.792427] g_ffs: Unknown symbol ffs_name_dev (err 0)
[ 1356.798698] g_ffs: Unknown symbol usb_add_config (err 0)
insmod: ERROR: could not insert module g_ffs.ko: Unknown symbol in module
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# modprobe g_ffs.ko dules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
modprobe: FATAL: Module g_ffs.ko not found in directory /lib/modules/4.9.56-linaro-lt-qcom
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg
gacy# inaro-alip:/lib/modules/4.9.56-linaro-lt-qcom/kernel/drivers/usb/gadget/leg

Unknown symbol means that your module depends on chunk of code that is currently missing in the kernel, usually because it is supposed to be provided by another module. modprobe is supposed to load the dependencies (not insmod). I think you need libcomposite.ko to be loaded prior g_ffs in your case.

Adding module libcomposite really works, now lsmod can check that the module has been loaded, thank you.
Now I want to add adb and fastboot functions on Debian, and I will configure it according to yocto system. After loading this module and related scripts, adb function does not work normally. May I ask if there is any relevant scheme for adding adb function on db4 Debian.thanks

Normally adb is an Android things. Through it seems possibel to have it on GNU/Linux: Adb daemon on 410c Linux

Fastboot is implemented by the bootloader… not sure why you want that running on Linux.